crawfish vs rock lobster

crawfish

noun
  • Various freshwater crustaceans, crayfish. 

  • Various marine crustaceans, rock lobster; especially Jasus lalandii, the Cape crawfish. 

  • A slur against Anglo-Canadians used in some corners of Quebec (including the Gaspé). 

verb
  • To backpedal, desert or withdraw (also used with out). 

rock lobster

noun
  • A crustacean of the family Palinuridae. 

How often have the words crawfish and rock lobster occurred in a corpus of books? (source: Google Ngram Viewer )